Britain\'s biggest retailer Tesco said on Thursday that sales had fallen for a fourth quarter in a row at its British stores, citing \"challenging\" economic conditions for consumers. The supermarket giant said underlying sales dropped 0.9 percent in the group\'s third quarter, or 13 weeks to November 26, mirroring the decline in its second quarter. \"UK consumers remain under pressure from rising unemployment, falling real wages and increasing living costs,\" Tesco said in its trading update. The company is the world\'s third-largest retailer after US-based Wal-Mart and France\'s Carrefour. Tesco added that total sales, including performance of its international stores, rose 7.2 percent in the third quarter. \"We have made good progress in our third quarter against the background of challenging conditions for consumers in many of our markets,\" chief executive Philip Clarke said in the group\'s trading update.